U.S. patent number 4,048,345 [Application Number 05/654,447] was granted by the patent office on 1977-09-13 for coffee percolation process.
This patent grant is currently assigned to General Foods Corporation. Invention is credited to Saul Norman Katz.
United States Patent |
4,048,345 |
Katz |
September 13, 1977 |
**Please see images for:
( Certificate of Correction ) ** |
Coffee percolation process
Abstract
A percolation process is described wherein it is possible to
operate a fixed-capacity percolator set at decreased capacity
without experiencing operational difficulties or coffee extract
quality loss. The extraction columns of the percolator set are
filled with the amount of roasted and ground coffee desired to be
extracted and the remainder of the column is filled with an inert
packing material.
Inventors: |
Katz; Saul Norman (Monsey,
NY) |
Assignee: |
General Foods Corporation
(White Plains, NY)
|
Family
ID: |
27023693 |
Appl.
No.: |
05/654,447 |
Filed: |
February 2, 1976 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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417312 |
Nov 19, 1973 |
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Current U.S.
Class: |
426/432; 422/261;
426/388 |
Current CPC
Class: |
A23F
5/262 (20130101); A23F 5/267 (20130101) |
Current International
Class: |
A23F
5/26 (20060101); A23F 5/24 (20060101); A23F
001/08 () |
Field of
Search: |
;23/272R,272AH,272.5
;426/425-436,388 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Coffee Processing Technology by Sivetz and Foote, published by Avi
Pub. Co., Westport, Conn., 1963, pp. 347, 348, 368. .
Coffee Processing Technology, vol. 2, by M. Sivetz, published by
Avi Pub. Co., Westport Conn.; 1963, pp. 171-172..
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Primary Examiner: Lutter; Frank W.
Assistant Examiner: Greenblum; N.
Attorney, Agent or Firm: Kornutik; Richard
Parent Case Text
This is a continuation-in-part of Application Ser. No. 417,312,
filed Nov. 19, 1973, now abandonded.
Claims
I claim:
1. In a percolation process wherein roasted and ground coffee is
loaded into a series of fixed volume extraction columns in a manner
such that said roasted and ground coffee exhibits packed bed
characteristics and is concurrently contacted with an aqueous
extraction liquid, the improvement whereby uniform quality and
operating characteristics are obtained at reduced output rates,
said improvement comprising loading spent coffee grounds and roast
ground coffee into said extraction columns to obtain a packed bed
such that said aqueous extraction liquid entering said columns
contacts said spent grounds prior to contacting the roasted and
ground coffee to be extracted whereby said packed bed
characteristics are maintained throughout the extraction
process.
2. The process of claim 1 wherein said spent coffee grounds do not
exceed about 35% by weight of the total column load.
Description
BACKGROUND OF THE INVENTION
This invention relates to coffee and more particularly to a
percolation process wherein coffee solids are extracted from
roasted and ground coffee to produce a coffee extract which is then
further processed to form a dry soluble coffee product.
Percolation is the semi-continuous countercurrent extraction of
water soluble coffee solids from roasted and ground coffee.
Percolation is performed in a percolation set which is comprised of
a series of extraction columns, generally 4 to 6.
At steady-state operation, the extraction columns of the percolator
set are filled with roasted and ground coffee of varying degrees of
extraction or freshness. An aqueous extraction liquid, generally
water, is heated and fed to the entrance of the extraction column
containing the most extracted roasted and ground coffee in the
percolator set, generally known as the spent stage extraction
column. The extraction liquid passes through the spent stage
contacting the roasted and ground coffee contained therein and
exits the extraction column as a dilute solution of coffee solids.
The extraction liquid is then passed to and through the next
successive extraction column containing the next most extracted
coffee in the percolator set, extracting soluble solids therefrom.
In like manner the extraction liquid is passed through successive
extraction columns containing progressively fresher or less
extracted roasted and ground coffee. The extraction liquid is
finally passed through the extraction column containing the least
extracted or freshest coffee in the set, generally unextracted
coffee, known as the fresh stage extraction column and a
predetermined portion of the extraction liquid is drawn off as
coffee extract thus completing a cycle. This coffee extract
generally contains from 20% to 35% soluble coffee solids by weight
and is then further processed to produce a dry soluble coffee
product.
A new cycle is begun by taking the spent stage extraction column
off-stream and placing a new extraction column generally containing
unextracted roasted and ground coffee on-stream thus becoming the
fresh stage for draw-off of coffee extract in this cycle. Aqueous
extraction liquid is then fed to the spent stage extraction column
for this cycle, the coffee contained therein being the next most
extracted coffee from the previous cycle, and extraction continues
as described above with the extraction liquid contacting
progressively fresher roasted and ground coffee.
It can be seen, then, that a given charge of roasted and ground
coffee becomes progressively more extracted in each successive
cycle.
There are numerous factors that affect the proper loading of a
coffee column in preparation for extraction. Some are percolator
wall temperature, rate of coffee fill into the percolator column,
size and shape of ground coffee bins, uniformity of grinds, and
slackness in percolator column fill.
Coarse particles in a free fall tend to roll to the edge of a bin.
Fines and chaff settle later in the corners of square bins and at
the edges of round bins. This phenomenon occurs in all the bins in
which the ground coffee is handled, as well as in the percolator
column under gravity fall of ground coffee. Faster filling of a bin
or percolator column traps particles as they fall so segregation is
minimized. Fast filling of the column is attained by sucking the
ground coffee in with air and removing the air from inside the
column. The fast fill has the advantage of giving higher coffee
loadings in the column by about 10 per cent over gravity fill.
Higher coffee column loadings mean higher productivity from the
percolator system and a few percent higher extract concentrations.
Denser column loadings reduce channeling of extract flow which is
more important in larger diameter columns. Uniformly fine grinds
also give less particle segregation and higher density of fills.
Additionally, steam at about 90 p.s.i. to about 150 p.s.i. is
employed to further compress or pack the coffee loaded within the
columns. Steam packing allows additional coffee to be admitted to
the column which is again steam packed. Roasted and ground coffee
loaded into percolator columns is described by those skilled in the
art as exhibiting a packed bed character.
A slack coffee bed results in mixing of extracts and channeling
which reduces extraction efficiency and gives lower extract
concentrations and lower solubles yields. The values of the snug
high density vacuum fill of dry ground coffee are that the coffee
bed is rigid, a swelling of 7 per cent after wetting further
reduces void, and extract flow is through a uniformly supported bed
and flow path. Prewetting of ground coffee before filling the
column will reduce frequency of excessive pressure drop, but this
type of slackness results in stale flavored coffee, looser beds
with channeling and lower extract concentrations.
In commercial percolation processes extraction columns are
completely filled with roasted and ground coffee and are sized such
that the appropriate amount of coffee extract is produced. Further,
commercial percolation processes are operated at cycle times, i.e.,
the time between successive draw-offs of coffee extract from the
fresh stage, which are relatively short so as to more economically
produce coffee extract. The coffee extract drying system is
similarly fashioned to accommodate the maximum percolation output.
The net result of this type of operation is a relatively
fixed-capacity system. However, there often exists the need for
operating a given percolator set at capacities below the maximum
for which it was designed. It is further essential, of course, that
the overall quality of the resultant coffee extract not be
diminished.
SUMMARY OF THE INVENTION
It has been found that it is possible to operate a fixed-capacity
percolator set at decreased capacities without encountering
operational difficulties or coffee extract quality loss by loading
the extraction columns of the percolator set with the amount of
roasted and ground coffee to be extracted and filling the remaining
area in the column with an inert packing material.
Various means of reducing the percolator output result in serious
operational difficulties and/or a decrease in the quality of the
resultant coffee extract. Loading the extraction columns with only
that amount of roasted and ground coffee to be extracted leads to
extremely troublesome operation. The coffee is loosely packed
within the fixed-volume extraction column and results in a
migration of coffee particles, particularly those of fine particle
size which can lead to excessive pressure buildups. Further, the
packed coffee will begin to separate on contact with the extraction
liquid and move into the free spaces of the column. The resultant
loss of the packed bed character leads to excessive channelling and
bypassing of the coffee which results in extremely poor extraction
of the soluble solids therefrom. There results uneconomical
operation and a possible quality decrease since many flavorful
coffee solids are left unextracted.
While reduced capacity can be achieved using a column completely
filled with coffee by utilizing long cycle times, it has been found
that operation in this manner is deleterious to the quality of the
coffee extract due to the degradation of flavorful coffee solids
during prolonged contact with hot extraction liquid.
According to this invention, however, it is possible to operate the
percolator set at reduced capacity without encountering any of the
above-mentioned problems.
DETAILED DESCRIPTION OF THE INVENTION
According to this invention, the percolator set is operated with
its extraction columns completely filled to avoid pressure problems
and uneconomical operation and at normal cycle times so as to avoid
adversely affecting the quality of the coffee extract.
In general, it is possible according to this invention to operate
at reduced capacities in the order of about 0.6 the normal
fixed-volume capacity. This will require generally the utilization
of packing material not in excess of about 35% by weight of the
overall column load.
The inert packing material utilized in the process of this
invention should contain little or no extractable material or
characteristic odor which would adversely affect the flavor and
aroma of the ultimate coffee extract. The material should be
capable of being packed within the extraction column with a minimum
of large void spaces. Suitable inert packing materials are the
commonly-employed column packings such as Raschig rings, Berl
saddles, Pall rings, Lessing rings, and the like. Examples of these
are set out in Perry's Chemical Engineer's Handbook, 18-26 (4th ed.
1963, McGraw-Hill).
A particularly useful and our preferred packing material is spent
coffee grounds defined as roasted and ground coffee which has been
fully extracted during the percolation process. The spent coffee
grounds should be dried and screened to break up any lumps of
material before use in the extraction column. While by definition
having little if any extractable material, the spent grounds may
impart an undesirable aroma note to the coffee extract in some
cases. Accordingly, it is preferred to "dearomatize" the spent
coffee grounds prior to their use as a packing to remove all such
extractable aromas and/or flavors. This may be suitably
accomplished by contacting the spent coffee at temperatures in the
range of 200.degree. F to 300.degree. F. It may also be preferred
to first wash the spent coffee grounds to remove any extraction
liquid that may be adhering thereon.
The amount of roasted and ground coffee to be extracted and the
inert packing material may be interspersed in a random fashion
within the extraction column. However, our preferred embodiment of
this invention separates the packing material from the roasted and
ground coffee which is to be extracted. Preferably, the extraction
column is separately loaded such that the entering aqueous
extraction liquid first contacts the inert packing material prior
to contacting the roasted and ground coffee to be extracted. Thus
for an extraction column operated in the upflow direction, the
requisite amount of inert packing would be loaded into the bottom
of the extraction column and then the roasted and ground coffee to
be extracted is loaded thereon to fill the column.
It is found that this type operation is particularly useful where
the inert packing material is spent coffee grounds. The effect of
any aromas from the spent coffee being picked up by the extraction
liquid and drawn off in the coffee extract is minimized by virtue
of a "filtering" effect of sorts which the roasted and ground
coffee to be extracted has on these aromas.
Further, regardless of the packing material, operation in the above
manner is found to result in more efficient extraction of the
roasted and ground coffee by virtue of the fact that uniform flow
patterns are developed in the packing before contact with the
roasted and ground coffee to be extracted.
The inert packing material may also be alternatively layered with
the roasted and ground coffee to be extracted or loaded into both
the top and bottom of the extraction column.
The roasted and ground coffee to be extracted may be decaffeinated
or undecaffeinated coffee and may be a single coffee variety or a
blend of coffee varieties. The aqueous extraction liquid, while
generally water, may also be any solution of soluble solids such as
salts or soluble coffee solids. The extraction liquid is generally
heated to between 300.degree. F to 350.degree. F before being fed
to the spent stage extraction column and it is generally desired to
draw off coffee extract from the fresh stage extraction column at
temperatures below about 220.degree. F. Suitable intercolumn
heaters or coolers may be employed according to well-known prior
art processes to achieve this or any other desired temperature
profile across the percolator set.
The following example will serve to more fully illustrate the
process of this invention.
A percolator set comprised of six extraction columns capable of
holding 1800 lbs. of roasted and ground coffee at normal operation
is operated at a capacity 0.6 times the normal. The extraction
columns of the percolator set are first loaded with 100 lbs. of
spent coffee grounds and then with 1080 lbs. of roasted and ground
coffee to be extracted in which is distributed an additional 376
lbs. of spent coffee grounds. The remainder of the extraction
column is filled with 100 lbs. of spent coffee grounds, The total
column load is 1656 pounds (owing to the fact that the spent coffee
grounds have a 20% lower bulk density than the roasted and ground
coffee to be extracted) of which 34.8% by weight is spent coffee
grounds. The percolator set is then operated at standard cycle
times (about 15 to 30 minutes) without experiencing operating
difficulties or a decrease in the quality of the resultant coffee
extract.
Numerous other reduced output rates can be achieved by varying the
amounts of roasted and ground coffee to be extracted and the inert
packing material. The ability to operate over a wide range of
varying output rates greatly increases and enhances the flexibility
of the percolation system.
The spent coffee grounds are prepared for use as the packing
material in the following manner. A portion of the spent coffee
removed from the spent stage extraction column after completion of
a cycle is screened to remove any free liquid and then further
washed with water to remove any adhering extraction liquid. The wet
spent coffee grounds are then fed to a dryer and dried with hot air
at about 200.degree. F to 300.degree. F to about 10% moisture. Any
lumps of spent coffee grounds are then broken up and the grounds
are screened to remove those particles which pass through an 8 mesh
screen.
While the foregoing invention has been described with respect to
specific examples and embodiments thereof they are presented for
illustrative purposes. It is believed that various modifications
and variations may be practiced without departing from the scope or
spirit of the invention as defined by the appended claims.
* * * * *